1. Field of the Invention
The present invention relates to a multi ceramic layer-coated metal plate and a process for manufacturing the same. The multi ceramic layer-coated metal plate of the present invention is weather resistant and provides pleasing decorative effects when used in interior decoration and for buildings and automobiles, etc.
2. Description of the Related Art
Due to the development and growth of electronics technologies, dry processes such as physical vapor depositions and chemical vapor depositions can be now applied to an improvement of the surfaces of metal materials. Namely, it is now possible to provide metal materials with a ceramic coating, which cannot be obtained except for an oxide by a wet process, a typical example being the electroplating processes of the prior art, and to provide the metal materials with weather resistance, abrasion resistance, decorative appearance, and infra-red characteristics.
Nevertheless, it is still difficult to replace the wet process with the dry process on an industrial scale, except for products with special functions, because the dry process is not suitable for mass production and has problems of high running costs and expensive apparatus.
Only one example of commercial success in the field of decoration is known, i.e., the gold color coating of titanium nitride on watches. This gold color coating is successful because it provides a watch with a high quality appearance. Nevertheless, it is still difficult to provide other colors by a dry deposition of a ceramic coating, because there are not many ceramic materials having a characteristic color, and currently only gold, black, gray, etc. can be obtained by the dry process.
Nevertheless, it is known that various colors can be obtained interference of light in a coating (see, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 54-66385 and 54-85214). But the obtained colors vary greatly depending on the angle of view, and thus their value as decorative products is low. Further, an extremely precise control of the uniformity of the thickness of the coating is required to obtain a uniform color, because the color varies in accordance with the thickness of the coating, and in practice, this means that the above coating cannot be applied to a product having a large area, such as a part of a building.
Further, although ceramic coatings providing a color as described above are resistant to weather, corrosion, abrasion, and so on, due to use of ceramics, these resistances are not high enough for applications such as parts of buildings and automobiles, etc.